搜题请搜索小程序“爱下问搜题”
问题 选择题

用NA表示阿伏加德罗常数的值．下列叙述正确的是（　　）

A．1.2 g NaHSO4晶体中阳离子和阴离子的总数为0.03 NA

B．100 mL 18.4 mol•L-1硫酸与足量铜反应，生成SO2的分子数为0.92 NA

C．1 L 1 mol•L-1的K2CO3溶液中离子总数小于3NA

D．室温下，42.0 g乙烯和丙烯的混合气体中含有的碳原子数为3NA

答案

A、1.2 g NaHSO4晶体物质的量=

1.2g
120g/mol
=0.01mol，硫酸氢钠晶体的微粒是钠离子和硫酸氢根离子构成，阳离子和阴离子的总数为0.02 NA，故A错误；

B、浓硫酸与铜反应，随着反应进行浓度变稀，稀硫酸不与铜反应，生成SO2的分子数小于0.92 NA，故B错误；

C、碳酸根离子水解CO32-+H2O⇌HCO3-+OH-；阴离子数增多，所以1 L 1 mol•L-1的K2CO3溶液中离子总数大于3NA，故C错误；

D、乙烯和丙烯最简式相同，质量换算物质的量，计算42gCH2中的碳原子数即可；含有的碳原子数=

42g
14g/mol
=3mol，即为3NA，故D正确；

故选D．

单项选择题

红外吸收光谱中，出现在1900～1650cm-1的最强峰是

A．羟基
B．羧基
C．芳香环
D．羰基
E．酚性羟基
查看答案
单项选择题

Many foreigners who have not visited Britain call all the inhabitants English, for they are used to thinking of the British Isles as England. (1) , the British Isles contain a variety of peoples, and only the people of England call themselves English. The others (2) to themselves as Welsh, Scottish, or Irish, (3) the case may be; they are often slightly annoyed (4) being classified as "English".

Even in England there are many (5) in regional character and speech. The chief (6) is between southern England and northern England. South of a (7) going from Bristol to London, people speak the type of English usually learnt by foreign students, (8) there are local variations.

Further north regional speech is usually " (9) " than that of southern Britain. Northerners are (10) to claim that they work harder than Southerners, and are more (11) They are open-hearted and hospitable; foreigners often find that they make friends with them (12) Northerners generally have hearty (13) : the visitor to Lancashire or Yorkshire, for instance, may look forward to receiving generous (14) at meal times.

In accent and character the people of the Midlands (15) a gradual change from the southern to the northern type of Englishman.

In Scotland the sound (16) by the letter "R" is generally a p sound, and "R" is often pronounced in words in which it would be (17) in southern English. The Scots are said to be a serious, cautious, thrifty people, (18) inventive and somewhat mystical. All the Celtic peoples of Britain (the Welsh, the Irish, the Scots) are frequently (19) as being more "fiery" than the English. They are (20) a race that is quite distinct from the English. (289 words)

Notes: fiery 暴躁的，易怒的。

（10）（）

A.used

B.apt

C.possible

D.probable
查看答案